1. Field of the Invention
This invention relates to power supplies and, more particularly, to DC to DC converters such as that described in U.S. Pat. No. 4,017,784 (issued to the assignee of this invention) in which the output voltage is regulated against variations in the input voltage. Such a DC to DC converter is often used to provide a high voltage DC output when only a low voltage DC source is available.
2. Description of the Prior Art
The DC to DC converter described in the above-mentioned patent contains a transformer having a primary and secondary winding and a predetermined leakage reactance existing between the primary and the secondary winding. A rectifier circuit is connected to the secondary winding and a large filter capacitance is connected to the rectifier to form an output across the filter capacitor adapted for connection to a load. A pair of electronic switches are connected across the input to the converter. A capacitor is included in series with the primary winding and voltage clamping diodes are connected across the primary winding to prevent voltage thereacross from exceeding a predetermined voltage level. Pulse generating means monitor the load voltage level and provide suitable pulses to the electronic switches to cause the switches to alternately conduct current through the capacitor and through the primary. The capacitive reactance of the capacitance is selected to bear a proper relationship to the inductance of the primary and the leakage reactance reflected from the secondary to provide a half sinusoid shaped current waveform through the primary during the operation of each switch. Furthermore, the periodicity of the pulses applied to the switches by the pulse generating means is increased or decreased as a function of the load voltage.
One of the limiting characteristics of such a converter is the amount of power which can be handled by the switching transistors. Since this power is limited by the peak current through the switching transistors, changing the primary circuitry so that the ratio of average to peak current is higher will allow greater total power to be handled by the converter.
It is an object of the present invention to provide a new and improved DC to DC converter.
It is another object of the present invention to provide a DC to DC converter having increased power handling capabilities.
It is still another object of the present invention to provide a DC to DC converter having unique pulse shaping characteristics in the primary circuitry.